In the related art, electric field communication using fluctuation of an electric field is known. For example, Patent Literature 1 describes a communication apparatus that performs the electric field communication via a human body. The communication apparatus can perform both of wireless communication via an antenna and the electric field communication via the human body. As shown in FIG. 1 of Patent Literature 1, a conductor plate as an electrode at a human body side for the electric field communication is arranged near the antenna of the wireless communication. In addition, a sum of a line length of a signal wire from a terminal on a substrate to the conductor plate and half a circumferential length of the conductor plate is equal to integral times of half the wavelength of a resonance frequency of the antenna. In this manner, deterioration of performance of the antenna is avoided (paragraphs [0012], [0028], or the like of specification of Patent Literature 1).